Three terminal magnetic sensor for magnetic heads with a semiconductor junction and process for producing same

ABSTRACT

The TTM sensor includes a semiconductor structure and a spin valve structure, where the semiconductor structure includes at least two layers. Two of the three leads of the TTM sensor are engaged to the semiconductor layers, where a semiconductor junction between the layers is disposed between the two leads. Generally, the junction may comprise a P-N junction between a P-type layer and an N-type layer and in an embodiment of the present invention the collector lead is engaged to the P-type semiconductor layer and the base lead is connected to the N-type semiconductor layer. The spin valve structure is fabricated upon the semiconductor structure and the emitter is engaged to the spin valve structure. In this configuration, a free magnetic layer of the spin valve structure is fabricated upon the semiconductor material, such that a schottky barrier is formed between the metallic free magnetic layer material and the semiconductor material.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to three terminal magneticsensors such as spin valve transistor sensors for magnetic heads, andmore particularly to a spin valve transistor sensor in which the baseand collector are formed within the semiconductor layers of the sensor.

2. Description of the Prior Art

Magnetic heads for hard disk drives are generally fabricated with a readhead portion and a write head portion. Currently, the typical read headportion of such magnetic heads includes a type of spin valve sensor thatis referred to as a giant magnetoresistance (GMR) sensor. Such GMRsensors include two electrical signal leads, and changes in electricalresistance of layers within the GMR sensor caused by the presence ofmagnetic data bits proximate the read head modulate the current of themagnetic head electronic sensor circuit. The fabrication characteristicsof such sensors are well known to those skilled in the art.

Efforts to create more sensitive read head sensors have recently lead tothe development of three terminal magnetic sensors, such as spin valvetransistor (SVT) sensors. In such devices, the components of a typicalspin valve sensor are fabricated upon a semiconductor layer, and threeelectrical leads, emitter, base and collector are utilized. One such SVTsensor for a magnetic head is described in published U.S. PatentApplication U.S. 2003/0214763 A1, published Nov. 20, 2003. The SVTsensors described in this published application include configurationsin which the semiconductor is connected to the collector lead andcomponents of the spin valve structure are connected to the emitter andbase leads. The SVT sensor of the magnetic head of the present inventionis fabricated with a different structure.

SUMMARY OF THE INVENTION

The magnetic head of the present invention includes a three terminalmagnetic (TTM) sensor, for example, a spin valve transistor (SVT) sensorwithin its read head. The SVT sensor includes a semiconductor structureand a spin valve structure, where the semiconductor structure includesat least two layers. Two of the three leads of the SVT sensor areengaged to the semiconductor layers, such that a semiconductor junctionbetween the layers is disposed between the two leads. Generally, thejunction may comprise a P-N junction between a P-type layer and anN-type layer and in an embodiment of the present invention the collectorlead is engaged to the P-type semiconductor layer and the base lead isconnected to the N-type semiconductor layer. The spin valve structure isfabricated upon the semiconductor structure and the emitter is engagedto the spin valve structure. In this configuration, a free magneticlayer of the spin valve structure is fabricated upon the semiconductormaterial, such that a barrier, for example a schottky barrier, is formedbetween the metallic free magnetic layer material and the semiconductormaterial. The schottky barrier is thus disposed between the emitter andbase leads of the SVT sensor. Various forms of the spin valve structureare contemplated for use with the layered semiconductor structure,including the use of a tunnel barrier layer within the spin valvestructure.

It is an advantage of the magnetic head of the present invention that ithas an TTM sensor in which two leads are engaged to semiconductormaterial layers.

It is another advantage of the magnetic head of the present inventionthat it has an SVT sensor in which the collector and base leads areengaged to P-type and N-type semiconductor material layers respectively.

It is a further advantage of the magnetic head of the present inventionthat it includes an SVT sensor in which a P-N junction is formed insemiconductor material between the base and collector.

It is yet another advantage of the magnetic head of the presentinvention that it includes an SVT sensor in which the emitter isconnected to a spin valve structure and the base and collector are bothconnected to semiconductor material structures.

It is yet a further advantage of the magnetic head of the presentinvention that it includes an SVT sensor wherein a schottky barrier isfabricated between the emitter and base.

It is an advantage of the hard disk drive of the present invention thatit includes a magnetic head of the present invention which has an TTMsensor in which two leads are engaged to semiconductor material layers.

It is another advantage of the hard disk drive of the present inventionthat it includes a magnetic head of the present invention that has anSVT sensor in which the collector and base leads are engaged to P-typeand N-type semiconductor material layers respectively.

It is a further advantage of the hard disk drive of the presentinvention that it includes a magnetic head of the present invention thatincludes an SVT sensor in which a P-N junction is formed insemiconductor material between the base and collector.

It is yet another advantage of the hard disk drive of the presentinvention that it includes a magnetic head of the present invention thatincludes an SVT sensor in which the emitter is connected to a spin valvestructure and the base and collector are both connected to semiconductormaterial structures.

It is yet a further advantage of the hard disk drive of the presentinvention that it includes a magnetic head of the present inventionhaving an SVT sensor wherein a schottky barrier is fabricated betweenthe emitter and the base.

These and other features and advantages of the present invention will nodoubt become apparent to those skilled in the art upon reading thefollowing detailed description which makes reference to the severalfigures of the drawing.

IN THE DRAWINGS

The following drawings are not made to scale as an actual device, andare provided for illustration of the invention described herein.

FIG. 1 is a top plan view generally depicting a hard disk drive of thepresent invention that includes a magnetic head of the presentinvention;

FIG. 2 is a side cross-sectional view depicting a prior art magnetichead;

FIG. 3 is an elevational view taken from the air bearing surface of theSVT sensor read head portion of the prior art magnetic head depicted inFIG. 2;

FIG. 4 is a diagram of the prior art SVT sensor depicted in FIG. 3 thatis useful for describing its electrical properties;

FIG. 5 is an elevational view taken from the air bearing surfacedepicting a three terminal magnetic (TTM) sensor of the presentinvention;

FIG. 6 is a diagram of the TTM sensor depicted in FIG. 7 that is usefulfor describing its electrical properties;

FIG. 7 is an elevational view taken from the air bearing surfacedepicting another TTM sensor of the present invention;

FIG. 8 is a diagram of the TTM sensor depicted in FIG. 7 that is usefulfor describing its electrical properties;

FIGS. 9, 10, 11 and 12 depict process steps for the fabrication of theTTM sensor of the magnetic head of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a top plan view that depicts significant components of a harddisk drive which includes the magnetic head of the present invention.The hard disk drive 10 includes a magnetic media hard disk 12 that isrotatably mounted upon a motorized spindle 14. An actuator arm 16 ispivotally mounted within the hard disk drive 10 with a magnetic head 20of the present invention disposed upon a distal end 22 of the actuatorarm 16. The magnetic head 20 is fabricated upon a larger substrate basetermed a slider 24. A typical hard disk drive 10 may include a pluralityof disks 12 that are rotatably mounted upon the spindle 14 and aplurality of actuator arms 16 having a slider 24 with a magnetic head 20mounted upon the distal end 22 of each of the actuator arms. As is wellknown to those skilled in the art, when the hard disk drive 10 isoperated, the hard disk 12 rotates upon the spindle 14 and the slideracts as an air bearing that is adapted for flying above the surface ofthe rotating disk. Such sliders with the magnetic heads are fabricatedin large quantities upon a wafer substrate and subsequently sliced intodiscrete devices 24.

A typical prior art magnetic head structure is next described with theaid of FIGS. 2-4 to provide a basis for understanding the improvementsof the present invention. As will be understood by those skilled in theart, FIG. 2 is a side cross-sectional view that depicts portions of aprior art magnetic head 30, FIG. 3 is an elevational view of a spinvalve transistor (SVT) sensor read head portion of the prior artmagnetic head 30 depicted in FIG. 2, taken from the air bearing surfaceof FIG. 2, and FIG. 4 is a diagram of the SVT sensor of FIG. 3 that isuseful in describing the electrical properties of the sensor.

As depicted in FIGS. 2 and 3, a typical prior art magnetic head 30includes a substrate base 32 with a spin valve transistor (SVT) sensor40, comprising a plurality of layers of specifically chosen materialsfabricated thereon. As is best seen in FIG. 3, the SVT sensor 40 is acurrent perpendicular to the plane (CPP) device, and includes asemiconductor layer 42, typically composed of silicon and having athickness of approximately 1 μm that is fabricated upon the substrate32. The semiconductor layer 42 is engaged to a first electrical leadthat serves as the collector 44 of the SVT sensor.

A free magnetic layer 46 is next fabricated upon the semiconductor layer42, and may be comprised of a substance such as NiFe with a thickness ofapproximately 2 nm. As is well known to those skilled in the art, thefree magnetic layer 46 is formed with a magnetization that is free torotate in the presence of the external magnetic field that emanates frommagnetic data bits disposed within the data tracks of the hard disk 12of the hard disk drive 10. The free magnetic layer 46 is connected to asecond electrical lead and serves as the base 48 of the SVT sensor. Themetallic free magnetic layer at the face of the semiconductor layer cancreate an electron barrier, termed a schottky barrier 49, between thebase 48 and the collector 44, as is described in detail herebelow. Athin alumina layer 50, which serves as a tunnel barrier layer is nextdeposited upon the free layer 46 to a thickness of approximately 5 Å to10 Å. Thereafter, a pinned magnetic layer 52 is fabricated upon thealumina layer 50. The pinned magnetic layer 52 is typically comprised ofa magnetic material such as CoFe or NiFe, and is formed with a thicknessof approximately 20 nm. The pinned magnetic layer 52 is connected to athird electrical lead that serves as the emitter 53 of the SVT sensor,such that the tunnel barrier 50 is thus disposed between the emitter 53and the base 48. Thereafter, an antiferromagnetic (AFM) layer 54 isdeposited upon the pinned magnetic layer 52, where the AFM layer istypically comprised of a material such as PtMn or IrMn and has athickness of approximately 15 nm.

The SVT sensor layers are then masked and milled to the read track widthW, and insulation material 56 such as alumina is deposited along sidethe sensor layers, such that the electrical sense current between theemitter, base and collector will flow through the sensor layers.Thereafter, a second magnetic shield (S2) 58 is fabricated upon the AFMlayer 54. Alternatively, the AFM layer 54 or the S2 shield 58 may serveas the emitter lead. An electrical insulation layer 59 is then depositedupon the S2 shield 58, and a write head portion of the magnetic head 30is next fabricated.

As is best seen in FIG. 2, an embodiment of the write head portion ofthe prior art magnetic head 30 includes a first magnetic pole (P1) 60that is fabricated upon the insulation layer 59. Following thefabrication of the P1 pole 60, a write gap layer 72 typically composedof a non-magnetic material such as alumina is deposited upon the P1 pole60. This is followed by the fabrication of a P2 magnetic pole tip 76 andan induction coil structure, including coil turns 80, that is thenfabricated within insulation 82 above the write gap layer 72.Thereafter, a yoke portion 84 of the second magnetic pole is fabricatedin magnetic connection with the P2 pole tip 76, and through back gapelement 90 to the P1 pole 60. Electrical leads (not shown) to theinduction coil are subsequently fabricated and a further insulationlayer 114 is deposited to encapsulate the magnetic head. The magnetichead 30 is subsequently fabricated such that an air bearing surface(ABS) 116 is created. Alternatively, other write head configurations asare known to those skilled in the art may be fabricated upon the SVTsensor 40.

It is to be understood that there are many detailed features andfabrication steps of the magnetic head 30 that are well known to thoseskilled in the art, and which are not deemed necessary to describeherein in order to provide a full understanding of the presentinvention.

FIG. 4 is a diagram of the prior art SVT sensor 40 depicted in FIG. 3that is useful for describing the electrical properties of the SVTsensor. As depicted therein, the pinned magnetic layer 52 which isengaged to the emitter 53 is shown with a general magnetization (arrow130) that is shown, for example, in the up direction. This up directionmagnetization 130 will generally favor the rapid, easy passage ofemitter electrons having an upward spin direction, whereas electronshaving a downward spin direction will generally be scattered within thepinned magnetic layer of the emitter. The alumina tunnel barrier layer50 forms a first barrier for the movement of electrons towards the baseand collector. Higher energy electrons, typically with an upward spin,although a lesser percentage with a downward spin, will travel throughthe barrier layer 50 to the free magnetic layer 46 which is engaged tothe base 48 of the SVT sensor. As indicated above, the magnetization ofthe free magnetic layer 46 rotates due to the influence of the data bitmagnetic fields. Where the magnetization of the free magnetic layer isrotated towards the up direction (arrow 134), the electrons having anupward spin travel rapidly and easily through the free magnetic layer.Those electrons having a downward spin are impeded and scattered withinthe free magnetic layer 46 and form much of the electrical current ofthe base 48 of the SVT sensor. Where the magnetization of the freemagnetic layer is towards the down direction (arrow 138) the oppositeeffect upon the electron spin and travel of the electrons occurs.

A second barrier in the form of a schottky barrier 49 is created at theinterface between the metallic free magnetic layer 46 and thesemiconductor layer 42 which is connected to the collector lead 44. Theelectrons with an upward spin, where the magnetization of the freemagnetic layer 46 is up (arrow 134), have the energy to cross theschottky barrier 49 and comprise substantially all of the electricalcurrent at the collector 44 of the SVT sensor. Electrons with a downwardspin (where the free magnetic layer magnetization is up) typically lackthe energy to get over or through the schottky barrier 140.

It is therefore to be understood that the SVT sensor 40 is formed withtwo barriers, the tunnel barrier 50 and the schottky barrier 49. Two ofthe SVT electrical leads, emitter 53 and base 48, are connected to spinvalve component layers, the pinned magnetic layer 52 and the freemagnetic layer 46 respectively, and one of the SVT leads, the collectorlead 44, is engaged to the semiconductor layer 42.

FIGS. 5 and 6 depict features of a three terminal magnetic (TTM) sensorin the form of an SVT sensor 200 of a magnetic head 210 of the presentinvention, which can serve as a magnetic head 20 within the hard diskdrive 10. FIG. 5 is an elevational view taken from the air bearingsurface (similar to the direction of FIG. 3), and FIG. 6 is a diagramthat is useful for describing the electrical properties of the SVTsensor 200. As will be understood from the following description, thesignificant differences between the magnetic head 210 of the presentinvention and the prior art magnetic head 30 depicted in FIGS. 2-4relate to the structure of the SVT sensor 200; other features andstructures of the magnetic head 210 of the present invention may besimilar to those of the prior art.

As depicted in FIG. 5, the magnetic head 210 includes a substrate base32 with a spin valve transistor (SVT) sensor 200, comprising a pluralityof layers of specifically chosen materials fabricated thereon. As isbest seen in FIG. 5, the SVT sensor 200 includes a semiconductor layer220, typically comprised of silicon and having a thickness ofapproximately 1 μm. The present is not be limited to the siliconsemiconductor material, and other semiconductor materials, such as GaAsmay be utilized. The semiconductor material 220 is doped with a suitablematerial such as boron to form a P-type semiconductor layer 224. TheP-type semiconductor layer 224 is engaged to a first electrical lead andserves as the collector 226 of the SVT sensor 200.

Upper portions of the P-type semiconductor layer 224 are further dopedto become an N-type semiconductor 228 through the addition of a dopingmaterial such as phosphorous. An N-P junction 230 is formed at theinterface between the N-doped layer 228 and the P-doped layer 224, andthe N-type semiconductor layer 228 is engaged to a second electricallead that serves as the base 232 of the SVT sensor 200.

A free magnetic layer 240 is fabricated upon the N-type semiconductorlayer 228, and it may be comprised of a material such as NiFe, with athickness of approximately 2 mn. The free magnetic layer 240 is formedwith a magnetization that is free to rotate in the presence of theexternal magnetic field that emanates from magnetic data bits disposedwithin the data track 12 of the hard disk of the hard disk drive 10. Athin alumina layer 244, having a thickness of approximately 5 Å to 10 Å,and which serves as a tunnel barrier layer is next deposited upon thefree layer 240. Thereafter, a pinned magnetic layer 248 is fabricatedupon the alumina layer 244. The pinned magnetic layer 248 is typicallycomprised of a magnetic material such as CoFe or NiFe, and is formedwith a thickness of approximately 2 nm. Thereafter, an antiferromagnetic(AFM) layer 256 is fabricated upon the pinned magnetic layer 248, wherethe AFM layer is typically comprised of a material such as IrMn or PtMnand has a thickness of approximately 10-15 nm. The pinned magnetic layer248 (or AFM layer 256) is connected to an electrical lead that serves asthe emitter 260 of the SVT sensor 200.

The SVT sensor layers are then masked and shaped to the read track widthW, and insulation material 264 such as alumina is deposited along sidethe sensor layers, such that the electrical sense current between theemitter, base and collector will flow through the sensor layers.Thereafter, a second magnetic shield (S2) 58 is fabricated upon the AFMlayer 256. Alternatively, the S2 shield 58 may serve as the emitterlead. An electrical insulation layer 59 is then deposited upon the S2shield 58, and a write head portion of the magnetic head 210 is nextfabricated as has been described above with the aid of FIG. 2. The writehead portion may be fabrication in other well known configurations asare known to those skilled in the art.

It is to be understood that there are many detailed features andfabrication steps of the magnetic head 210 that are well known to thoseskilled in the art, and which are not deemed necessary to describeherein in order to provide a full understanding of the presentinvention.

FIG. 6 is a diagram of the SVT sensor 200 depicted in FIG. 5 that isuseful for describing its electrical properties. As depicted therein,the pinned magnetic layer 248 which is engaged to the emitter 260 isshown with a general magnetization in the up direction (arrow 270). Thisup direction magnetization will generally favor the rapid, easy passageof electrons having an upward spin direction, whereas electrons having adownward spin direction will generally be scattered within the pinnedmagnetic layer of the emitter 260. The alumina tunnel barrier layer 244forms a first barrier that controls the movement of electrons towardsthe base and collector. Electrons, typically with an upward spin willhave greater probability of travel through the tunnel barrier 244 andthe free magnetic layer 240, although a lesser percentage of electronswith a downward spin will have a greater probability of being scatteredbefore traveling through the tunnel barrier 244 and the free magneticlayer 240. As indicated above, the magnetization of the free magneticlayer rotates due to the influence of the data bit magnetic fields.Where the magnetization of the free magnetic layer 240 is towards the updirection (see arrow 274), the electrons having an upward spin travelrapidly and easily through the free magnetic layer 240. Electrons havinga downward spin are impeded and scattered within the free magneticlayer. A second barrier 278 in the form of a schottky barrier is formedat the interface between the metallic free magnetic layer 240 and theN-type semiconductor material 228 which is connected to the base 232.The electrons with an upward spin have the energy to cross the schottkybarrier 278, where a lesser percentage of downward spin electrons canpass over or through the schottky barrier. Thereafter, the electronstravel from the N-type semiconductor 228 to the P-type semiconductor224, and a third barrier exists at the junction 230 between the N and Ptype semiconductor layers 228 and 224. Electrons with sufficient energyto cross the N-P junction barrier 230 will be collected at the collector226 as the collector current, while electrons without sufficient energywill form the current at the base lead 232 from the N-type semiconductorlayer 228.

It is therefore to be understood that the SVT sensor is 200 formed withthree barriers, the tunnel barrier 244, the schottky barrier 278 and theN-P junction barrier 230. Two of the SVT electrical leads, the base 232and the collector 226, are connected to semiconductor component layers,the N-type semiconductor layer 228 and the P-type semiconductor layer224 respectively, and one of the SVT leads, the emitter lead 260, isengaged to the spin valve at the AFM layer 256 or pinned magnetic layer248. The emitter 260 thus can be said to be connected to the spin valvestructure, and the base and collector are connected to layers of thesemiconductor 220.

FIGS. 7 and 8 depict features of another three terminal magnetic (TTM)sensor device in the form of an SVT sensor 300 of a magnetic head 310 ofthe present invention, which can serve as the magnetic head 20 in thehard disk drive 10, where FIG. 7 is an elevational view taken from theair bearing surface (similar to the direction of FIGS. 3 and 5), andFIG. 8 is a diagram that is useful for describing the electricalproperties of the SVT sensor 300. As will be understood from thefollowing description, the significant differences between the magnetichead 310 of the present invention and the prior art magnetic head 30depicted in FIGS. 2-4 relate to the structure of the SVT sensor 300;other features and structures of the magnetic head 310 of the presentinvention may be similar to those of the prior art.

As depicted in FIG. 7, the magnetic head 310 includes a substrate base32 with a spin valve transistor (SVT) sensor 300, comprising a pluralityof layers of specifically chosen materials formed thereon. As is bestseen in FIG. 7, the SVT sensor 300 includes a semiconductor layer 320,typically comprised of silicon and having a thickness of approximately 1μm. The semiconductor material 320 is doped with a suitable material toform a P-type semiconductor layer 324, and suitable doping material isboron. The P-type semiconductor layer 324 is engaged to a firstelectrical lead and serves as the collector 326 of the SVT sensor.

Upper portions of the P-type semiconductor layer 324 are further dopedto become an N-type semiconductor 328 through the addition of a dopingmaterial such as phosphorous. An N-P junction 330 is formed at theinterface between the N-doped layer 328 and the P-doped layer 324, andthe N-type semiconductor layer 328 is engaged to a second electricallead that serves as the base 332 of the SVT sensor 300.

A free magnetic layer 340 is fabricated upon the N-type semiconductorlayer 328, and it may be comprised of a material such as NiFe with athickness of approximately 2 nm. The free magnetic layer 340 is formedwith a magnetization that is free to rotate in the presence of theexternal magnetic field that emanates from magnetic data bits disposedwithin the data track 12 of the hard disk of the hard disk drive 10. Anon-magnetic, electrically conductive spacer layer 344, typicallycomprised of Cu or Ru and having a thickness of approximately 1 mn, isnext deposited upon the free layer 340. Thereafter, a pinned magneticlayer 348 is fabricated upon the spacer layer 344. The pinned magneticlayer 348 is typically comprised of a magnetic material such as CoFe orNiFe, and is formed with a thickness of approximately 2 nm. Anantiferromagnetic (AFM) layer 356 is next fabricated upon the pinnedmagnetic layer 348, where the AFM layer is typically comprised of amaterial such as IrMn or PtMn and has a thickness of approximately 10-15nm. The pinned magnetic layer 348 (or AFM layer 356) is connected to anelectrical lead that serves as the emitter 360 of the SVT sensor 300.

The SVT sensor layers are then masked and shaped to the read track widthW, and insulation material 364 such as alumina is deposited along sidethe sensor layers, such that the electrical sense current between theemitter, base and collector will flow through the sensor layers.Thereafter, a second magnetic shield (S2) 58 is fabricated upon the AFMlayer 356. Alternatively, the S2 shield 58 may serve as the emitterlead. An electrical insulation layer 59 is then deposited upon the S2shield 58, and a write head portion of the magnetic head 310 is nextfabricated as has been described above with the aid of FIG. 2. The writehead portion may be fabrication in other well known configurations asare known to those skilled in the art.

It is to be understood that there are many detailed features andfabrication steps of the magnetic head 310 that are well known to thoseskilled in the art, and which are not deemed necessary to describeherein in order to provide a full understanding of the presentinvention.

FIG. 8 is a diagram of the SVT sensor 300 depicted in FIG. 7 that isuseful for describing its electrical properties. As depicted therein,the pinned magnetic layer 348 which is engaged to the emitter 360 isshown with a general magnetization in the up direction (arrow 370). Thisup direction magnetization will generally favor the rapid, easy passageof electrons having an upward spin direction, whereas electrons having adownward spin direction will generally be scattered within the pinnedmagnetic layer of the emitter 360. The spacer layer 344 then allows thetravel of electrons therethrough to the free magnetic layer 340. Asindicated above, the magnetization of the free magnetic layer 340rotates due to the influence of the data bit magnetic fields. Where themagnetization of the free magnetic layer 340 is towards the up direction(see arrow 374), the electrons having an upward spin travel rapidly andeasily through the free magnetic layer 340. Electrons having a downwardspin are impeded and scattered within the free magnetic layer. A firstbarrier in the form of a schottky barrier 380 is formed at the interfacebetween the metallic free magnetic layer 340 and the N-typesemiconductor material 328 which is connected to the base 332. Theelectrons with an upward spin have the energy to cross the schottkybarrier 380, where a lesser percentage of downward spin electrons canpass over or through the schottky barrier. Thereafter, the electronstravel from the N-type semiconductor to the P-type semiconductor, and asecond barrier exists at the junction 330 between the N and P typesemiconductor layers. Electrons with sufficient energy to cross the N-Pjunction barrier 330 will be collected at the collector 326 as thecollector current, while electrons without sufficient energy will formthe current at the base 332 from the N-type semiconductor layer 328.

It is therefore to be understood that the SVT sensor is 300 formed withtwo barriers, the schottky barrier 380 and the N-P junction barrier 330.Two of the SVT electrical leads, the base 332 and the collector 326, areconnected to semiconductor material layers, the N-type semiconductorlayer 328 and the P-type semiconductor layer 324 respectively, and oneof the SVT leads, the emitter lead 360, is engaged to the spin valve AFMor pinned magnetic layer 348. The emitter thus can be said to beconnected to the spin valve structure, and the base and collector areconnected to layers of the semiconductor material.

Process steps for fabricating the SVT sensor of the magnetic head of thepresent invention are next described with the aid of FIGS. 9-12. Asdepicted in FIG. 9 and with reference to the magnetic head embodiment210 depicted in FIGS. 5 and 6, a semiconductor substrate layer 220 isdeposited upon or bonded to the surface of the substrate 32 utilizingsputter deposition or similar well known techniques. Alternatively thesemiconductor substrate may comprise the substrate 32 and be separatefrom the substrate as part of a silicon on insulator (SOI) process as isknown to those skilled in the art. The semiconductor substrate 220 maybe comprised of various semiconductor materials such as silicon andgallium arsenide, and/or a silicon on insulator (SOI) layered structure.The semiconductor substrate layer having a thickness of approximately 1μm is then doped, preferable with a P dopant such as boron to a depth404 of at least approximately 0.2 μm within the substrate layer 220.Thereafter, as depicted in FIG. 10, the P-doped semiconductor layer 224is exposed to an N-doping process to achieve a relatively shallowN-doped surface layer 228 portion having a thickness of at leastapproximately 0.1 μm within the P-doped semiconductor. The quantity ofN-dopant such as phosphorous exceeds that of the P-dopant in therelatively shallow layer 228, such that the layer acts as an N-dopedlayer 228 and there is a P-N junction 230 between the P-doped layer 224and the N-doped layer 228. Process techniques for P and N doping thesemiconductor substrate are well known to those skilled in the art and adetailed description thereof is not deemed necessary for anunderstanding of the present invention.

Thereafter, as depicted in FIG. 11, a central portion of thesemiconductor layer is masked, followed by a material removal step, suchas a sputter etching or ion milling step, in which the outer portions408 of the semiconductor substrate are removed, down through the P-Njunction 230 and into the P-doped semiconductor layer 224. Thereafter,the various layers of materials that comprise the spin valve sensor aredeposited upon the substrate. As indicated hereabove, the spin valvelayers may include a free magnetic layer 240, a tunnel barrier layer 244or a spacer layer, a pinned magnetic layer 248 and an antiferromagneticlayer 256. Thereafter, a further mask is fabricated to protect thecentrally located spin valve layers, and outer portions 412 of the spinvalve layers are removed, such as by sputter etching, ion milling orother material removal techniques. Thereafter, electrical interconnectleads are fabricated to the various layers; particularly, a collectorlead 226 is fabricated in connection with the P-doped semiconductorlayer 224, a base lead 232 is fabricated in connection with the N-dopedsemiconductor layer 228 and the emitter lead 260 is fabricated inconnection with the upper layers of the spin valve structure, such asthe antiferromagnetic layer 256.

The thickness and doping levels of the N-type semiconductor layer 228can be controlled with thermal annealing and diffusion techniques todiffuse the N-type semiconductor dopant material into the surface of aP-type semiconductor 224. The barrier 230 between the N and P-type canbe modified by the semiconductor doping levels or by a biasing voltageon the N-type semiconductor or the P-type semiconductor. The area ofoverlap between the N-doped semiconductor layer 228 and P-dopedsemiconductor layer 224 is desirably minimized because if the N-typelayer 228 has a very large area over the P-type layer 228 then basicallyit can cause excessive current leakage from the N-type semiconductor tothe P-type semiconductor; so the overlap area of the N-type layer 228 onthe P-type layer 224 should be minimized. It is also to be noted thatthe order of N-type semiconductor on P-type semiconductor can bereversed in the present invention. Therefore a TTM sensor of the presentinvention can have a P-N junction or a N-P junction therein.

While the present invention has been shown and described with regard tocertain preferred embodiments, it is to be understood that modificationsin form and detail will no doubt be developed by those skilled in theart upon reviewing this disclosure. It is therefore intended that thefollowing claims cover all such alterations and modifications thatnevertheless include the true spirit and scope of the inventive featuresof the present invention.

1. A three terminal magnetic (TTM) sensor, comprising: a firstsemiconductor component of said sensor that is engaged to a first sensorlead; a second semiconductor component of said sensor that is engaged toa second sensor lead.
 2. A sensor as described in claim 1 furtherincluding a spin valve component of said sensor that is engaged to athird sensor lead.
 3. A sensor as described in claim 1, wherein saidfirst semiconductor component is engaged to a collector lead and saidsecond semiconductor component is engaged to a base lead.
 4. A sensor asdescribed in claim 3 wherein said first semiconductor component iscomprised of P-type semiconductor material and said second semiconductorcomponent is comprised of N-type semiconductor material.
 5. A sensor asdescribed in claim 2, wherein said third sensor lead is an emitter lead.6. A sensor as described in claim 1, wherein said first semiconductorcomponent is comprised of P-type semiconductor material and said sensorlead is a collector lead; said second semiconductor component iscomprised of N-type semiconductor material and said second sensor leadis a base lead; and said sensor further includes a spin valve componentincluding a pinned magnetic layer and a free magnetic layer, and whereina third sensor lead that comprises an emitter lead is engaged to saidspin valve component.
 7. A sensor as described in claim 6, wherein saidfree magnetic layer is disposed next to said N-type semiconductormaterial such that a schottky barrier is formed therebetween, and a P-Njunction is formed between said P-type semiconductor material and saidN-type semiconductor material.
 8. A sensor as described in claim 7,wherein said schottky barrier is formed between said emitter lead andsaid base lead, and wherein said P-N junction is formed between saidbase lead and said collector lead.
 9. A three terminal magnetic (TTM)sensor, comprising: a spin valve structure and a semiconductorstructure; and at least one electron barrier, wherein said barriercomprises a semiconductor junction within said semiconductor structure.10. A sensor as described in claim 9 wherein said semiconductor junctionis a P-N junction.
 11. A sensor as described in claim 10, wherein aP-type semiconductor material of said P-N junction is connected to afirst sensor lead of said sensor, and an N-type semiconductor materialof said P-N junction, is connected to a second sensor lead of said SVTsensor.
 12. A sensor as described in claim 11, wherein said first sensorlead comprises a collector lead of said sensor, and said second sensorlead comprises a base lead of said SVT sensor.
 13. A sensor as describedin claim 9, wherein said semiconductor junction is disposed between abase lead and a collector lead of said sensor.
 14. A sensor as describedin claim 9, wherein said spin valve structure is connected to an emitterlead of said sensor.
 15. A sensor as described in claim 14, wherein saidspin valve structure includes a tunnel barrier layer.
 16. A sensor asdescribed in claim 14, wherein said sensor includes a schottky barrierand a P-N junction.
 17. A sensor as described in claim 12, wherein saidspin valve structure is connected to an emitter lead of said sensor, andwherein a schottky barrier is disposed between said emitter lead andsaid base lead, and said P-N junction is disposed between said base leadand said collector lead.
 18. A hard disk drive including a magnetic headincluding a three terminal magnetic (TTM) sensor, comprising: a firstsemiconductor component of said sensor that is engaged to a first sensorlead; a second semiconductor component of said sensor that is engaged toa second sensor lead.
 19. A hard disk drive as described in claim 18further including a spin valve component of said sensor that is engagedto a third sensor lead.
 20. A hard disk drive as described in claim 18,wherein said first semiconductor component is engaged to a collectorlead and said second semiconductor component is engaged to a base lead.21. A hard disk drive as described in claim 20 wherein said firstsemiconductor component is comprised of P-type semiconductor materialand said second semiconductor component is comprised of N-typesemiconductor material.
 22. A hard disk drive as described in claim 19,wherein said third sensor lead is an emitter lead.
 23. A hard disk driveas described in claim 18, wherein said first semiconductor component iscomprised of P-type semiconductor material and said sensor lead is acollector lead; said second semiconductor component is comprised ofN-type semiconductor material and said second sensor lead is a baselead; and said sensor further includes a spin valve component includinga pinned magnetic layer and a free magnetic layer, and wherein a thirdsensor lead that comprises an emitter lead is engaged to said spin valvecomponent.
 24. A hard disk drive as described in claim 23, wherein saidfree magnetic layer is disposed next to said N-type semiconductormaterial such that a schottky barrier is formed therebetween, and a P-Njunction is formed between said P-type semiconductor material and saidN-type semiconductor material.
 25. A hard disk drive as described inclaim 24, wherein said schottky barrier is formed between said emitterlead and said base lead, and wherein said P-N junction is formed betweensaid base lead and said collector lead.
 26. A method for fabricating athree terminal magnetic (TTM) sensor of a magnetic head, comprising:fabricating a P-type semiconductor material; fabricating an N-typesemiconductor material at an upper surface of a portion of said P-typesemiconductor material; fabricating a spin valve structure upon saidN-type semiconductor material; engaging a collector lead to said P-typesemiconductor material; engaging a base lead to said N-typesemiconductor material; and engaging an emitter lead to said spin valvestructure.
 27. A method for fabricating a TTM sensor as described inclaim 26, including the steps of fabricating a schottky barrier betweensaid N-type semiconductor material and said spin valve structure.
 28. Amethod for fabricating a TTM sensor as described in claim 26, whereinsaid step of fabricating an N-type semiconductor material includes thesteps of doping an upper layer of said P-type semiconductor material tocreate said N-type semiconductor material.